Doctor operating mechanism for rolls and cylinders



May 4, 1943. F. W.-LODDING DOCTOR OPERATING MECHANISM FOR ROLLS AND CYLINDERS I Filed Dec. 9, 1938 3 Sheets-Sheet 1 INVENTOR Fi'caer/clrM Zdad/ ATTORNEY -May-4, 1943. F. w. LODDING V 8,

DOCTOR OPERATING MECHANISM FOR ROLLS AND CYLINDERS Filgd Dec. 9, 1938 3 Sheets-Sheet 2 WM ATTORNEY May 4,1943. F. w. LODDING DOCTOR OPERATING MECHANISM FOR ROLLS AND CYLINDERS Filed Dec. 9, V1938 s Sheets-Sheet 5 INVENTOR M mmy.

T37. EY

Patented ay 4, l9

STATES time one neuron or: nous 'rnzo MECHANISM non an I 1' "l- BB Frederick w. Loading," Worcester, 7

Application December 9, 1938, Serial No. 244,824

' 4 Claims.

The resent invention relates to devices known in the paper. making art as doctors or scrapers, such devices being customarily employed'in connection with rotating calender rolls, press rolls, drier cylinders and the like, for the purpose of and partially in section, along the line cleaning the surfaces of such rolls and cylinders.

In the operation of a doctor, it is desirable to move the doctor blade back and forth in a direction parallel to the axis of the rotating surface being doctored, since such reciprocatory movement tends to reduce and equalize wear on the roll surface, and obtains better resultsior a given pressure exerted by the doctor blade. While mechanisms for imparting reclprocatory movement to doctors have heretofore been employed, such mechanisms have been in the'nature oi auxiliary attachments to existing doctor installations, with resulting complexity oi construction and obstruction of space usually available for access to the doctors and roll surfaces.

Furthermore, it has been'found that in some doctor installations, space factors make it practically impossible to apply any auxiliary operat- -ing mechanism.

According to the present invention, there is provided an improved doctor-operating mechanism of the above described character, in which the mechanism for imparting reclprocatory movement is-incorporated in the doctor assembly, so as to be disposed entirely within the pivotal supports for the doctor. As a result, doctor mechanisms embodying the present, invention can be installed in any desired location with ref erence to rolls and'cylin'ders, without having to consider space limitations which would render the application of an auxiliary operating'mechanism impossible. The above and other advantageous. features of the invention will hereinafter more fully appear from the following description with reference to the accompanying drawings, in which: I O

Fig. 1 is a view in end elevation, of a doctor mechanism embodying the present invention.

Fig. 2 is a longitudinal sectional view, along the line 2-2 01 Fig. 1.

Fig. 3 is a fragmentary sectional view, illustrating, on an enlarged scale, the control valve mechanism indicated in Fig. 2.

Fig.' 4 is a sectional view along the lined-d of Fig. 3, looking in the direction or the arrows.

of a lever l2, turnable on p pivot pin l3, mounted Fig. 7 is a view in end elevation of a modliied form of doctor operating mechanism.

Fig. 8 is a view partially in front elevaton,

bring the blade 6 into engagement with the rotating surface of the roll I. The particular construction of the holder 2 and blade d to no part of the present invention, which haste do .with improved mechanism for imparting a reciprocatory movement to the holder 2, so that: .the blade 4 will move back and iorth longitudinally of the surface being doctored. I The doctor-supporting arm 3 carries near its ends a air hf trunnions providing cylindrical housings 5, W1 each of which is received a journal 8. rigidly mounted on a machine frame member I. A suitable anti-friction bearing 8 is disposeclbetween each journals and the wall.

of the surrounding'housing 5, so that-the arm 8, together with the holder ii carrying the doctor blade 8, is free to-turn about a pivotal axis. parallel to the axis of rotation of the roll i. Each journal 6 carries'a piston 9 fitting closely within a housings 5, both housings b, together with the doctor arm- 3, being capable of-shiltlng movement as a unit on the stationary pistons 9. Each housing 5 is closed by a cap is beyond the piston 8, thereby providing an enclosed chamber II at the end of each housing 5.

As best shown in Figs. 3, .4 and 5, one chamber provides a control valve mechanism. consisting on a valve block ll carried by-the cap M. The lowerend oi the lever ii is connected by spring llto a stud 16, extending from the piston 9, so

that movement of, the housing 5 with respect to Fig. 5 is a sectional view along the line 5-5 of Fig. 3, lookingin the direction of the arrows.-

Fig. 6 shows the valve mechanism oi Flg. 43in a different position.

the piston 9, will impart turning movement to the lever l2.

-Th e upper-endof the lever l2 carrlesa valve .disl; H, which, as best shown in Fig. 5,-is movable with respect to a series of ports M, l 9 and 10, pro- 1 videdin the block ll. Theport i8 is incommunication'with a passage 2! extending through thecap ii to the outside atmosphere, while the through the block ll to a pipe 23 leading through the other cap I to the chamber ll, within the opposite-housing 5. The third port, 20, is connected by a passage 24 to a pipe 25, leading to a suitable source of suction, not shown, such as is often available on paper making machines, for suction boxes.

With the valve lever l2 in the position of Fig. 3, the disk I! bridges the ports 18 and I9, and a recess ll'a within the disk ll serves to connect the ports I8 and 19. As a result, the inside of the right-hand chamber II is open to atmospheric pressure through the pipe 23, the connected valve ports 18 and I9, and the passage 2|. Consequently, when the left-hand chamber H is subjected to suction through the pipe 24 and the then open port 20, atmospheric pressure entering the right-hand chamber H and also acting against the exterior of the left-hand chamber cap ID, will cause the housing 5, and with it the arm 3 and doctor blade 3, to be shifted to the left, -as viewed in Fig. 2.

When this shifting has caused the doctor blade 4 to reach the dotted line position of Fig. 2, movement of the pivot pin l3 for the lever l2, with respect to the fixed stud IE, will cause the springl5 to throw the lever l2 from the position of Fig. 3 to the position of Fig. 6. When this occurs, the shifting of the valve disk il', causes the port l8 to be uncovered, thereby admitting atmospheric pressure to the left-hand chamber v At the same time, the ports 5 9 and 28 will be placed in communication, thereby subjecting the right-hand chamber ii to the source of suction, through the pipe 23. The resulting force of atmospheric pressure acting in the left-hand chamber H, and against the right-hand chamber cap tion, as it is sometimes termed, is extremely.

effective in furthering the doctorin'g action of the blade in cleaning the roll I, since it tends to reduce and equalize wear of the roll surface, such as would not otherwise occur. Furthermore, it is apparent that installation of complete means for imparting 'reciprocatory. movement to the blade, is accomplished by merely mounting the supporting arm 3 between the journals 6, carried by the machine frame members 1. the entire operating mechanism is thus self contained within the extremities of the arm 3, makes it possible to readily install a reciprocating doctor in locations where space limitations would make it impossible to install an auxiliary doctor-opera ating mechanism. It is also to be noted that the provision of separate spaced chambers for the actuating medium, entirely eliminates the necessity for airtight stuffing boxes, such as would-be required for a double acting cylinder utilizing a pressure medium.

Referringnow to Figs. 7 and 8, there is shown a modified arrangementsof the doctor-operating mechanism, in which the disposition of the machine frame members Ia permits a trunnion arrangement extending beyond the ends of the arm 3a carrying the holder 2 and doctor blade I.

The fact that In thisconstruction, each end of the arm 3a sup ports a projecting cylindrical trunnion housing 26, providing an external groove 21 for receiving a curved saddle 28, best shown in Fig. 7. Thus, the weight of the doctor supporting arm 3a and the housings 26, issupported by the saddles 28,

with the entire assembly free to turn about an axis coinciding with the center of curvature of the saddles 28. Each saddle 28 is mounted for longitudinal movement on a pair of rollers 29, rotatably supported on divergent axes, by means of a bracket 30 secured to each frame member Ia. Thus, the whole doctor assembly is pivotally supported as a unit for back and forth movement by a suction-controlled mechanism similar to that previously described with reference to Figs. 1 and 2.

Each housing 26 surrounds a stationary piston head 3|, mounted on a .rod 32 extending from a bracket 33 carried by a frame member la. The pistons 3i therefore define chambers 34 Within the housings 26, and a valve operating lever i211 is mounted within one chamber ing of the valve lever I2.

, blade holder.

34, so as to function in exactly the same manner as the valve lever l2, previously described with reference to Figs. 3 to 6, inclusive. A pipe 35 leading from a suitable source of suction, leads into the left-hand chamber 3 3, while apipe 35 connects the chambers, so that as suction and atmospheric pressure are alternately applied to the chambers 35, the entire doctor assembly moves back and forth on the rollers 29, it being noted that the pistons 3! are entirely relieved of the weight of the doctor assembly. Since the rods 32 carrying the stationarypistons3l are adjustable within the brackets 33, the amplitude of the reciprocatory moveinent imparted to the doctor blade 4 can be readily varied by shifting the positions of the pistons 3! within the' housings 26.

From the foregoing, it is apparent that by the present inventionthere is provided an improved mechanism for imparting a back and forth or oscillatory movement to doctor blades, particularly characterized by the mounting of the entire operatingmechanism, to move as a unit with the arm which carries the doctor While the operating mechanism has been described as being actuated from a. suction source, obviously, it will function just as effectively when actuated by any pressure medium. For pressure operation, it is only neces-'- sary to connect pipe leading from a pressure source to the' valve passage 2|, while allowing the valve port 20 to exhaust the chambers to the atmosphere alternately through function- In operation of the mechanism constructed as shown in Figs. '7 and 8,- the amount of power required is small, due to the fact that the trunnion housings carrying the entire doctor assembly are supported for pivotal, as well as longitudinal, movement by the saddles and rollers entirely independent of the stationary pistons within the housings, so that frictional losses are reduced to a mini- I claim: I

1. A doctor operating mechanism-for rolls and cylinders of a. paper making machine, comprising in combination, spaced stationary frame members, a doctor blade, a carrier for said blade extending between said frame members, trunnions mounted on said carrier at its ends and providing hollow housings, means for rotatably and slidably supporting said trunnion housings on said frame members to position said carrier with the edge of said blade in engagement with a rotating surface, a piston carried by each frame member and extending within a trunnion housing, and valve means located in one housing and operated by relative movement between said housing and piston for controlling admission of a fluid operating medium to the trunnion housings, to impart a back and forth movement to said blade carrier with respect to said pistons and frame members, in a direction parallel to the axis of said rotating surface.

2. A doctor operating mechanism for rolls and cylinders of a, paper making machine, comprising in combination, spaced stationary frame members, a doctor blade, a carrier for said blade extending between said frame members, trunnions mounted on said carrier at its ends, and each providing a hollow housing, with said trunnion housings being disposed entirely between the extremities of said blade carrier, journals extending from said frame members into said housings for rotatably and slidably supporting said trunnions and carrier, with the edge of said blade in engagement with a rotating surface,

pistons carried by said journals and fitting witheach providing a hollow housing extending beyond the end of said carrier, means cooperating with the exterior of said housings for rotatably and slidably supporting said trunnions on said frame members to position said carrier, with the edge of its bladeinen agement with a rotating surface, pistons carriedby said frame members and fitting within said trunnion housings, and valve means located in one housing and operated by relative movement between said housing and piston for controlling the admission of a fluid operating medium to the trunin said housings, and valve means located in one housing and operated by relative movement between said housing and piston for controlling the admission of a fluid operating medium to the trunnion housings to impart a. back and forth movement to said blade carrier with re-" spect to said pistons and frame members, in a direction parallel to the axis of said rotating surface.

3. A doctor operating mechanism for rolls and cylinders of a paper making machine comprising in combination, spaced stationary frame members, a doctor blade, a carrier for said blade extending between said frame members, trunnions mounted on said carrier at its ends and nion housings, to impart a back and forth movement to said blade carrier with respect to said pistons and frame members, in a direction parallel to the axis of said rotating surface.

4. A doctor operating mechanism for rolls .and

cylinders of'a paper making machine, comprising in combination, spaced stationary frame members, a doctor blade, a carrier for said blade extending between said frame members, trunnions mounted on said carrier at its ends and each providing a hollow housing extending beyond the end of said carrier, saddles and rollers cooperating with said trunnions for rotatably and slidably supporting said carrier and blade assembly on said frame members to position said carrier, with the edge of its blade in engagement with a rotating surface, pistons carried by said frame members and fitting with-' in said trunnion housings, and valve means located in one housing and operated by relative movement between said housing and piston for controlling the admission of a fluid operating medium to the trunnion housings, to impart a back and forth movement to said blade carrier with respect to said pistons and frame members, in a direction parallel to the axis of said rotating surface.

' FREDERICK w. LODDING. 

